This recipe by a British-born pastry chef assumes the use of a kitchen scale to weigh ingredients. In parentheses, we’ve included approximate quantities measured in the more familiar cups and tablespoons.

To make cookies: Preheat oven to 325 degrees. Cream butter with both sugars until pale and fluffy. Mix in egg a little at a time and continue to cream mixture until smooth. Stir in vanilla and peanut butter until thoroughly combined.

Sift flour, baking soda, baking powder and salt together twice. Mix in oats, then tip all dry ingredients into creamed mixture. Stir well to form a soft dough (if you are using an electric mixer, do this by hand, with a wooden spoon).

Scoop 30 cookies onto baking sheets lined with baking parchment, spacing them 3 inches apart, as they spread during baking. Bake in center of oven about 15 minutes, until golden brown and firm to touch. Leave to cool on baking sheets.

Meanwhile, make peanut filling: Cream together butter and confectioners’ sugar until pale and fluffy; if using an electric mixer, do this with whisk attachment. Add peanut butter and mix just enough to combine.

When cookies are completely cold, pipe or spoon a generous amount of filling onto flat side of 15 of them, then sandwich them together in pairs with remaining cookies. There should be enough filling for it to show between cookies. They are best eaten on the day they are made, but they can be stored in an airtight container.